The invention relates to a releasable fastening device, especially for attachments on convertibles by means of which the attachment can be snapped without further aids on the vehicle body.
German DOS 3,112,214 makes known a roof-bearer attachment for motor vehicles, having supporting members which are mounted on a carrier part and to each of which a clamping strap is secured releasably by means of a tensioning device. The tensioning device comprises an eccentric, as a result of the rotational movement of which the clamping strap can be moved into the tensioning position and into the release position. Moreover, the eccentric is adjustable in its position relative to the supporting member and to the clamping strap by means of a setscrew completing the tensioning device, with the result that positional tolerances between the supporting member and the clamping strap can be compensated.
The production of the eccentric and the correspondingly adapted design of the curved bearing surface can only be seen as involving high manufacturing costs. The adaptation of the distance between the clamping strap and the supporting member to the distance tolerances occurring from the body receptacle to the bearing surface on the supporting member can also be achieved only with difficulty by means of a setscrew, since this should both be capable of being secured in its set position and, when the attachment is changed over, be adjustable again in a simple way.
An object on which the invention is based is to provide a fastening device of the relevant generic type which is easy to operate and which involves low production costs.
This object is achieved according to preferred embodiments of the invention by an arrangement wherein the tensioning device is formed only by a flexural spring which is pivotally mounted at one end on the hook part and at the other end on the attachment.
The flexural spring, which alone constitutes the tensioning device, on the one hand performs the function of bracing the hook part by pressing this against the receptacle in the convertible body and is at the same time also the link which mounts the hook part pivotally on the attachment. Furthermore, the flexural spring can also be reduced in length in a simple way, so that distance tolerances between the receptacle and attachment are compensated by its greater or lesser deflection.
This adaptation of the flexural spring to the existing distance between the receptacle and the attachment is also made easier by a predetermined constant curvature of the flexural spring between its secured ends in the direction of its pivoting plane.
The use of a leaf spring as a flexural spring is especially recommended, since a leaf spring is suitable both as a tensioning means of constant action and as a stable link.
Moreover, the hook part can be given such a body shape what it completely covers the flexural spring, at least when the latter is in the locking position, so that there is no danger of injury.
A fastening device of this type is expedient particularly for attachments which are to be removed and then mounted again relatively frequently, as is true, for example, of a wind guard comprising two frame bodies, of which an upper frame body can be erected as a windscreen and a lower frame body remains attached to the convertible body. This lower frame body covers the rear space of the convertible, but can be detached from this, as desired, by means of the releasable fastening device.
The receptacle for the hook part of the fastening device can be provided on a cover of a folding-top box, so that it is possible also to open the folding-top box cover together with the attachment secured to it and to unfold the folding top from the folding-top box.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.